1. Field of the Invention
This invention relates generally to transmission mounting device and more particularly to a shock and vibration damping system for transmissions such as marine transmissions.
2. Background Art
Various mounting systems have heretofore been employed for transmissions. German patent document DE OS 35 16 903, illustrated a transmission damping and positioning system which included a rigid bearing upon which the transmission was centrally supported in combination with laterally spaced yieldable mounts. The yieldable mounts comprised, for example, rubber buffers, springs, or shock absorbers and served to attenuate vibrations, changes in torque loads, structure borne vibrations and accompanying noises. In addition, the yieldable mounts also compensated for structural changes in the supporting base relative to the transmission. For example, a ship's hull was subject to deformation which resulted in variations between the relative positions of the ship's drive system including transmissions, motors and the bearings for the ship's screw shafts.
These structural deformations frequently led to damage of drive system components. As a result, the ship's screw shafts were required to be interconnected to transmissions through elastic couplings. The couplings utilized were relatively large, heavy and costly.
Due to the necessity of reducing relative displacement between drive system components, prior transmission bearings were required to be relatively hard. Transmission vibration, deformations of the hull, torque shocks or impacts from the motor or from the ship's screw shafts resulted in relatively significant positional changes of the transmission with respect to the remaining drive system components when yieldable elastic components were used for bearings.
The utilization of relatively hard bearings permitted compensation of some of the positional changes of the drive system components relative to one another. Utilization of relatively hard bearings did not adequately provide for noise attenuation or adequately compensate for system shocks. The degree of permitted elasticity was limited since excessive elasticity resulted in damage to the transmission, the motor or the screw shaft due to the relative movement of the components.
As a result of the conflicting requirements for transmission mounting systems, known mounting systems, at best, provided but a compromise with respect to desired results.